In U.S. Senate races this year, nine of the top ten recipients of lobbyist campaign contributions are Democrats. Banking Committee member Sen. Jon Tester, D-Mont., his office a hub of the bank-lobbyist revolving door, is unsurprisingly No. 1. The chart below comes from data compiled by the Center for Responsive Politics.

On one level, it makes perfect sense that the top recipients of lobbyist cash in the Senate races would be Democrats. Incumbents raise more than non-incumbents and most incumbents in close races this year are Democrats.

But that doesn't explain everything in the chart above.

Firstly, Sens. Bob Casey, D-Pa., Tim Kaine, D-Va., and Maria Cantwell, D-Wash., aren't in races any more competitive than their Republican colleagues whom they are massively outraising.

Secondly, Sen. Dean Heller, R-Nev., the most vulnerable Republican incumbent, comes in a lowly ninth, on this score, way behind plenty of Democrats who pose as populists, such as Sens. Sherrod Brown of Ohio and Heidi Heitkamp of North Dakota.

Thirdly, you'll notice the top non-senator there is Kyrsten Sinema – whose reputation as a moderate mostly means that she's a liberal who loves corporate welfare. Two of the top three non-senators on the list are Democrats.

On the House side, though, Republicans are dominating in lobbyist cash, mostly because of league-leading donations from the firm of former Ronald Reagan official Boyden Gray.

If Republicans maintain their lead in overall lobbyist contributions (House, Senate, incumbent, non-incumbent), it will be their first time winning that inauspicious contest since 2006. In the Obama era, Democrats dominated in the race for K Street cash, setting a record in 2010 that still stands today, of $26.8 million in lobbyist contributions in the failed effort to kill the Tea Party in the cradle.

But if Democrats take the Senate this year, that will mark a win for K Street.